1. Field of the Invention
The present invention relates to a resource reservation system and method in a multihoming environment. More particularly, the present invention relates to a resource reservation system and method for performing a resource reservation using a plurality of care of addresses (CoAs) through multiple network interfaces.
2. Description of the Related Art
In a mobile network configured with a plurality of mobile nodes, a predetermined amount of resources must be constantly provided by reserving them in order to guarantee a quality of service (QoS) of a multimedia application even though a mobile node performs a handover. Accordingly, a resource reservation is performed in the mobile network.
In a multihoming environment, a mobile node may have more than two network interfaces. Accordingly, QoS signaling may be performed by selecting one of the Network interfaces that can connect to a path having sufficient resources in the multihoming environment.
Conventional protocols proposed for QoS signaling are the Resource Reservation Protocol (RSVP), Extensions to Resource Reservation Protocol (E-RSVP), Mobile Resource Reservation Protocol (MRSVP), RSVP tunnel, Concatenation and Optimization for Resource reservation Path (CORP), Hierarchical Mobile RSVP (H-RSVP).
The RSVP protocol was proposed for a wired network. Accordingly, the RSVP protocol is not suitable for QoS signaling in a mobile network.
The E-RSVP protocol was developed by modifying the RSVP protocol in order to perform the QoS signaling in a mobile network. The E-RSVP protocol was designed to instantly reserve resources by requesting a PATH message when a mobile node performs a handover. However, the E-RSVP protocol is not suitable for a Sender-initiated resource reservation scheme which reserves resources by transmitting a resource reservation message from a sender.
The MRSVP protocol quickly provides the existing QoS even though a mobile node performs a handover. However, resources are wasted in a mobile network having insufficient resources because a mobile node previously reserves resources of an adjacent cell where the mobile node moves. Also, the reserved resources are not instantly released according to the MRSVP protocol.
The RSVP tunnel protocol provides a QoS in a tunnel. Initially, a RSVP protocol message was not recognized between an entry point of a tunnel and an exit point of a tunnel. The RSVP tunnel protocol solves such a conventional recognition problem. However, the RSVP tunnel protocol does not include a method for rapidly re-reserving resources when a mobile node performs a handover. Furthermore, the RSVP tunnel protocol unnecessarily re-reserves resources on the end-to-end level, and the RSVP tunnel protocol does not have a method of performing a Localized Path Repair by quickly finding a crossover node (CN) when a mobile node performs a handover.
The CORP protocol provides a QoS by expanding an existing resource reservation path using a conventional RSVP protocol when a mobile node performs a handover. In order to expand the resource reservation path, a concatenation for reservation path (CRP) scheme is used. However, the CORP protocol previously reserves resources of an adjacent cell, to which the mobile node moves, in a mobile network having insufficient resources. Also, the CORP protocol performs a point-to-point level resource reservation to reserve resources. Therefore, resources are wasted unnecessarily, according to the CORP protocol.
The H-MRSVP protocol is a resource reservation protocol developed by integrating the RSVP protocol with a regional registration function of a Mobile IP protocol. When a mobile node performs an inter-region handover, resources are reserved by using a reservation tunnel between a gateway mobility agent (GMA) and a new proxy agent. Although the H-MRSVP protocol performs a resource reservation only when a delay time of handover becomes longer, for example, the inter-region handover, the H-MRSVP protocol has a problem of resource usability caused by the unnecessary reservation.
The above-mentioned conventional resource reservation protocols have a common problem that QoS signaling is performed without using of the advantageous characteristics of multihoming. In multihoming, seamless transmission is provided through duplicated physical communication links when one of the physical communication links has a problem, and data traffic is dispersed into a plurality of communication links for improving QoS. Such an advantageous characteristic of multihoming is not supported by conventional resources reservation protocols.